The approximately 340,000-square-foot midtown south building is held by an anonymous family owner, people familiar with the property said. The building will likely require a substantial infusion of cash in the near future, a factor that is perhaps prompting the offering.

114 Fifth Avenue.

Grey Advertising has a healthcare group at the location that is set to relocate from the property in upcoming months, leaving vacant as much as 70,000 square feet. A person familiar with the condition of the building said it will likely require a renovation in order to lure potential tenants and that the current owner was considering a sale of the building’s leasehold so that it could select a capable real estate operator to invest the necessary capital and exert the kind of hands on management the property will likely require to operate at its full potential.

The owner, listed in mortgage documents as 114 Fifth Avenue Associates LLC, has hired the real estate services firm Wells Hill Partners to market the property. Wells Hill executives Peter Gevalt and Daniel Mizukovski would not comment on the sale.

A potential deal appears well timed. According to data released by the real estate services firm CBRE yesterday, the Midtown South neighborhood where 114 Fifth Avenue is located, is the strongest performing office market in the country. CBRE’s statistics showed that vacancy dropped to the lowest level in the city during 2011, falling from 12.5 percent to 8.8 percent year over year.

“Midtown South was supposed to be the cheaper market,” Mary Ann Tighe, CBRE’s New York area CEO said during the company’s presentation to the media at its midtown offices. “That has changed. It’s now a culture choice.”

Ms. Tighe noted that rents have risen in a select group of high end Midtown South buildings to higher rates than in Midtown, what is widely considered the city’s priciest office district.

“As more people are rehabilitating their buildings [in Midtown South], pricing is getting into the $60s and $70s per square foot,” Ms. Tighe said.

One broker not affiliated with the sale said that the building could fetch as much as $800 a square foot, a price that would put the property’s value at over $270 million.